Improvement in casters for furniture



UNITED STATES PATENT OFFICE.

WILLIAM A. PERKINS, OF SALEM, MASSACHUSETTS.

IMPROVEMENT IN CASTERS FOR FURNITURE.

Specification forming part of Letters Patent No. 159,352, dated February 2, 1875 application filed April 24, 1874.

To all whom it may concern:

Beit known that I, WILLIAM A. PERKINS, of Salem, in the county of Essex, in the State of Massachusetts, have invented a new Improvement in Casters, of which the following specication, with. its accompanying drawing, is a full, clear, and exact description.

The object of this invention is to furnish to the public a strong caster made of few parts, and one that will move in any direction with the minimum of friction; and it relates to a caster that has conical friction-rolls interposed between two plates, which have a conical or beveled surface next to the frictionrolls, and also to acaster, which has a screw cast solid or otherwise rmly attached to its upper plate, for the purpose of securing it `usually to articles of household furniture, and where the upper plate is made polygonal, so that a wrench may be easily applied to mount the caster. f\-

This invention consists in the combination of a loosely-revolving guard-frame, constructed with vertical grooves from top to bottom, with the upper and lower plates of a caster, constructed as described.

The figures in the drawing represent, 1, a vertical section of the whole caster; 2, a horizontal section of the guard, showing the friction-rolls in place; 3, a plan view of the caster; 4, a plan view of the vertically grooved guard-plate, 5, a section ofthe same.

A represents the caster-wheel, supported by arms B, cast as a part of the lower plate C, the upper surface of which is beveled. Resting upon this plate are conical frictionrolls H, having journals at each end that tit loosely in grooves a of the retlolving guardframe G. Covering this frame, but resting only upon the friction-rolls, is a hexagonal plate, E, beveled upon its under surface, so that the rolls lit nicely, but loosely, between these upper and lower plates. This beveled construction, obviously, is for the purpose of allowing the plates and friction-rolls to revolve with the slightest possible amount of friction. (last as a part of, or otherwise made solid to, the upper plate is a hollow screw, F, by which to attach the caster to any desired object. Extending through the whole length of this hollow screw is a pin, D, which, being fastened firmly to the lower plate, is the center of rotation for all the revolving parts. When the different parts are united this pin is slightly upset or headed at the manufactory, so `that the combination cannot drop apart.

The guard-frame Gr (shown as of hexagonal form merely to correspond in finish with -the upper plate) is constructed with vertical grooves a, which extend its whole depth, or, in other words, from top to bottom, and these grooves `act to keep the centers of the friction-rolls in lines radial from the center or axis of the guard-frame, permitting a vertical play of the journals of the friction-rolls during their rotation. This is the salient point, the chief novelty, in this inventionthe cutting in the guard-frame of vertical grooves from top to bottom, instead of only upon the under surface of the frame, whereby there is no chance for friction from binding of the parts, which will certainly result without these vertical grooves if the parts are not made with perfect accuracy, because upon a caster, which is a very small article as an entirety, several independent parts must turn, which collectively support oftentimes a very heavy weight.

In this invention the dierent partsthe fewest number practicable-are easily and firmly put together, and the combination cannot drop apart unless the caster should get broken.

Theperimeter of the upper plate being a polygon, a wrench may be quickly and surely applied to mount it.

Independently, or of themselves, a polygonal upper plate and hollow screw are old; and sois the pin for connecting the upper and lower plates together. Oonical friction-rolls and a guard to hold them are also old; but a loosely-revolving guard-frame with vertical grooves from top to bottom, in combination with these speciecl elements, is believed to be new; therefore,

I claim- The combination of a loosely-revolving guard-frame, G, provided with vertical grooves a from top to bottom, so as to hold the journals of friction-rollers, with the beveled polygonal plate E and its screw F, the beveled wheel-supporting plate C, and its pin l), and with the conical friction-rollers H, substantially as described.

Witnesses: WM. A. PERKINS.

`JoIIN A. BAssETT, I. R. NICHOLS. 

